This invention is directed to battery chargers and more particularly to battery chargers for recharging battery packs (for example, of nickel-cadmium cells) commonly used as a power supply for power tools, appliances and similar devices driven by small motors.
For cordless power tools, there are a wide variety of commercially available designs for removable, rechargeable battery pack power supplies. The designs have proliferated because of the evolution of power tools designs from a single manufacture as well as the different pack designs originating from different manufactures. As the designs are not standardized among manufacturers and not fully standardized by each individual manufacturer it has been necessary to provide a specialized charger for each of the various pack designs. Recently there has been a trend by individual manufacturers to increase the standardization of its packs for a variety of power tools and to provide chargers for recharging more than one of its pack designs.
One approach has been to provide a charger with multiple specialized receptacles. Each receptacle can receive only one pack design. This approach is disadvantageous because the resulting charger tends to be larger and more expensive because of the multiple receptacles. Another approach has been to provide a charger with a single receptacle and interchangeable inserts for the receptacle to accommodate different packs designs and is exemplified by German Patent Application No. DT 2,702,129. This approach has been found to be disadvantageous because the added cost of the interchangeable inserts and because of inconvenience of storing and retaining the inserts not in use. A third approach exemplified in U.S. Pat. No. 4,873,479 has been to provide a charger with a single large receptacle subdivided into two smaller chambers. One chamber corresponds to one battery pack design and the second portion corresponds to a second battery pack design. The third approach is disadvantageous because of the requirement to have a small chamber corresponding in size and shape to each pack design.
An object of this invention is to provide a more universal charger which may be used to recharge battery pack designs available from a number of manufacturers. Three commercially available battery pack designs which may be recharged in a battery charger in accordance with this invention are shown in FIGS. 10-12. FIG. 10 shows a battery pack 213 which is available from a single manufacturer (Black & Decker) and is currently used as a power supply for a plurality of power tools. Pack 213 has a transverse large oval cross-section (as shown in FIG. 10A) and has a pair of terminals 214 separated by an insulator 215 and shielded by shroud 217. FIGS. 11, 12 shows battery packs 219, 225 which are exemplary of battery pack designs available from a number of manufacturers and which are used as a power supply for a variety of power tools. Pack 219 has a transverse small oval cross-section (as shown in FIG. 11A) and has a pair of terminals 221 at opposed locations on the sidewall 223 of pack 219. Pack 225 has a D-shaped cross-section (as shown in FIG. 12A) and has a pair of terminals 227 at opposed locations on the sidewall 229 of pack 225.
The present invention overcomes many of the disadvantages associated with prior art battery chargers for a plurality of battery pack designs by providing a battery charger having a single receptacle (1) sized and shaped to accommodate one of a plurality of battery pack designs and (2) automatically adapted to receive alternate pack designs upon insertion of the alternate pack.
In accordance with another aspect of the invention, a charger comprises a housing and a receptacle for alternatively receiving a plurality of battery packs having different cross-sectional areas. The receptacle has a sidewall and an opening formed in a housing wall and circumscribing a first area. The area of the opening corresponds approximately to the transverse cross-sectional area of one of the packs. Electrical contacts in the receptacle electrically contact the respective terminals of the plurality of packs. A retractable abutment extends from the sidewall into the receptacle for abutting a second pack having a transverse cross-sectional area smaller than the area of the receptacle opening and smaller than the transverse cross-sectional area of the first pack. The abutment is resiliently retractable from the receptacle when the first pack is in the receptacle.
In accordance with a still further aspect of the invention, a charger comprises a universal receptacle which can accommodate a plurality of battery packs having different cross-sectional areas. The receptacle has opening that is sized to correspond approximately to the cross-sectional area of one of the packs. A pack positioning means in the receptacle positions a second pack smaller than the first pack to properly contact the electrical charger contacts. The positioning means is resiliently retractable when the first larger pack is inserted into the receptacle. The positioning means may be comprised by the pack locator or by the retractable abutment or by both.
Additional objects and advantages of the invention will be apparent from the detailed description of the preferred embodiment or may be learned by the practice of the invention.